Conventionally, as a hydraulic pressure supply system of this type, for example, one disclosed in PTL 1 has been known. The engine has an output shaft connected to drive wheels of a vehicle via a clutch and a belt-type continuously variable transmission. Further, the engine is automatically stopped when predetermined stop conditions are satisfied, and is restarted when predetermined restart conditions are satisfied during stoppage or traveling of the vehicle. The hydraulic pressure supply system has an oil pump, which uses the engine as a motive power source, for supplying hydraulic pressure to the clutch.
In the hydraulic pressure supply system, during automatic stop of the engine, the hydraulic pressure supplied to the clutch (hereinafter referred to as “the clutch supply hydraulic pressure”) is reduced from a predetermined hydraulic pressure. This releases the clutch to disconnect between the automatically stopped engine and the continuously variable transmission, whereby the belt of the continuously variable transmission is prevented from slipping with respect to a pulley during time from the automatic stop of the engine to the stop of the vehicle. Further, during the automatic stop of the engine, if the restart conditions are satisfied, a restarting operation is started to restart the engine, and the clutch supply hydraulic pressure is increased to the predetermined hydraulic pressure. This causes the clutch to connect between the engine and the continuously variable transmission, whereby the driving force of the engine is transmitted to the drive wheels via the clutch and the continuously variable transmission.